Engine noise and whooshing. When you start up from cold the viscous fan will be fully engaged so you can hear a whooshing noise. As the truck warms up the noise decreases quite a lot as the ram effect of moving at normal speeds takes over from the viscous effect.

The A/C fan shouldn't, I believe, wel according to RAVE, activate until the temperature ambient is 28C or the sensor stat demands the A/C condenser to be cooled if already moving or idling. If the A/C fan comes on immediately when starting from cold and the ambient temperature is below 28C then the sensor is likely to be defective or blocked.